I originally wanted a camera/laptop bag for travel, and then ended up not using it very much because the laptop compartment was wasted space since I would always leave the laptop in the hotel room.

The Crumpler Pretty Boy looks nearly identical in design to the Lowepro CompuDaypack which didn't work for me. The long lens didn't fit right in the padded areas where the camera is meant to be and again, the laptop compartment was only used in flight.

When I travel now, I stick my laptop in a laptop sleeve and pad it on both sides with clothes in a regular carry-on size suitcase. All my camera goodies go into my Lowepro Flipside 300, which can hold the 50 f/1.4 and the 100-400mm plus some bars of food, my wallet, a rain cover and my air blower. I could fit the kit lens in too, but I prefer that spot for a lightweight jacket.

Within your budget, the Case Logic SLRC-206 SLR Camera/Laptop Backpack seems to have the best design. You should be able to fit your current set-up plus future zoom lens in that as well as have it hold your laptop.